Home Forums Hunting & Shooting Gunsmithing What might cause this?

Here are a couple of pictures of a 204 case that was out of an AR 15... any idea why the case with the blown primer, also has a Weatherby "belt" on it...

a case was fired before this one, that does not have enough recoil to automatically cycle the bolt on the AR... is this possible by the previous shot partially cycling the bolt, and then the following one, cycling it the rest of the way and then some.. causing a head space issue and the belt being formed along with blowing the primer?





Thanks for your guys input on this...

Damn, glad it was you and not me pulling the trigger...looks like you were fortunate nothing worse happened. I can't tell you what caused this, but it looks like the belt must have been caused by ignition before the case was in battery. Is the neck really stretched? or is it just an optical illusion? That poor head really took a lickin...you did not mention if these were factory loads or hand loads. I'm sure some of the pros will weigh in in the morning.

should not have fired anyway without the bolt closing... firing pin or trigger issues maybe? not wanting anything bad to happen to you just really glad it wasn't me

post on the AR section also, may get an immediate "this happened to me"....

woofer

WOW... I've never seen something like THAT...

DO NOT fire that rifle again until someone who knows ARs checks that out..

You're lucky, this time..

the one on the right would tickle my short hairs. the one on the left would dirty the works

woofer

Looks like it fired out of battery.

Indeeeeedy do....

Gotta be impressed that case held together like it did though.

Interesting how the case on the right has a line right where the top of the "belt" is on the case that appears to have a belt. I'm wondering if this is related to the machining processes of the case or to the chamber of the rifle. I can't imagine the case would have fireformed that way in a baddly cut chamber and stayed intact. I'm also wondering if other cases exhibit less belted dimensions but are still out of spec enough to cause the short cycling you mention. I think I would be contacting Hornady about their brass, particularly if the chamber is cut correctly.

It did not fire out of battery unless both cases did, or it would be longer from streaching. if both cases are the proper length then you have a bad chamber which is what I suspect.

Send the rifle to the person that did the chanbering before you lose an eye or worse, it is totally unsafe.

I saw this over in the AR section and offered my inexpert opinion there. Will post it here for consideration.

Being a dropout from the redneck shadetree school of gunsmithy it looks like to me the cartridge head protrudes too much from the chamber in that particular rifle. Headspace may be or maybe was correct but case is unsupported near the case head from a too shallow of a chamber. I think the 'belted' round also had a pressure excursion-the brass must be tough or it would have completely blown. I don't know what the breech end of an AR barrel should look like but in this case it must look like the famed Rem 3 rings of steel with a recess for the bolt nose. Plateau Hunter
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I'm curious...were these cases some of your Blue Dot handloads?

What is so strange is that the cartridge on the left has an almost perfectly shaped belt, as from a factory belted cartridge.

It is difficult to believe that the case formed so perfectly from an accident.

After thinking about it some more wonder if the chamber was cut with a .20 Tactical reamer and subsequently the rifle was assembled and headspaced with a .204 gauge? Would that give a situation such as this? It is strange that the other cases looked pretty normal. Maybe the heavier case pushed the pressure over the edge to get this result in a short chamber. DPMS ought to take a look at this rifle and its .204 reamers imo.

Personally I don't think it fired out of battery as the case should be much longer and should have ruptured. A pressure spike at time of unlocking is way down the road from ignition and should have blown the bolt and carrier thru the buttstock right? Plateau Hunter

what would happen if the bolt chambered the round but failed to lock? the round is fired and the whole shebang goes backwards a few thou'. i still dont understand the perfect rim. it almost looks machined....

or, what if the firing pin hung up and never fully retracted? bolt shoved the case most of the way in and it fired before fully locking up. primer blows and case fly backwards bending things all up....

dunno'. i wish i knew more about ar's....

woofer

I'm not so sure it was out of battery.

It looks like excess pressure for sure though.

I'm thinking if it was out of battery, the shoulder would be moved forward and the neck would be shorter.

Maybe it didnt fire out of battery, but how about this....as the bolt slammed home it didnt fully lock and the gun was fired, upon firing since it was'nt locked it started cycling the bolt while the chamber was full of pressure causing the last part of the shell which is now exposed to start to expand causing the "belt"........maybe?????

Just run the case through a die and toss it in with the rest; I'm sure it's fine.

:-)

WOW. Scary stuff. I agree with the guys saying figure that out before shooting it again.

It pretty much has to be a slamfire, right?

-jeff

I don't know the history of the rifle, but is it possible that someone might have tried to rechamber it for use with a belted case, then didn't tell anyone?

The way that belt is formed on that case looks too precise to have been fired in a rifle with the bolt partially open.

If you can, could you measure the case on the belt and the rim and compare that measurement with the base on the normal case?

If the belt is larger than the case body, then there has to be a recess somewhere that the brass expanded into, to form the belt.

I am not familiar with the AR, but does the bolt face or the rear of the chamber have a recess or cut out that the case could have expanded into?

Another question. Was this cartridge actually fired in a rifle chambered for the .204 Ruger? It looks like it was fired in a rifle chambered for a belted case.

I'm wandering if the squib load fired before this one left the bullet in the barrel. Cause's high pressure on the second shot, which is also a squib. Bolt partially retracts, case begins to deform, second bullet pushes first bullet out of barrel, pressure bleeds off before anymore damage done. Look inside the barrel for a bulge ring. Sound feasable?

I don't know much about AR's as they aren't my cup of tea, so everything is a guess. Whatever happened, I believe you were being watched over from above.

Dave.